Various security systems require the use of biometric systems to provide access for an authorized person to a product, location or service or to authenticate the presence of an authorized person at a particular location. For example, security locks may be configured to be released when an approved fingerprint is scanned at a fingerprint scanner. Some personnel tracking system require an authorized person to scan an approved fingerprint at a fingerprint scanner to prove that the authorized person is present at the location of the fingerprint scanner. The use of biometric such as a fingerprint to identify an authorized person has the advantage that the authorized person is positively identified. Other persons typically do not share the same biometric. Depending on the nature of the scanner, it may be possible for an unauthorized person to present an approved fingerprint in the form of a two or three dimensional copy such as an image or model or as part of a severed finger. Fingerprints are essentially permanent characteristics of a person. An unauthorized person who is able to present an authorized fingerprint can only be stopped from gaining access by de-authorizing the fingerprint.
Some security systems avoid the problem of using an immutable biometric of an authorized person by using a passcode such as a password or a sequence of gestures. The passcode may be issued for use by an authorized person, and may be cancelled or replaced as needed when a person is no longer authorized or as a new passcode is needed. In addition a passcode has the advantage that it can be memorized or otherwise recorded by a person but is not an immutable physical characteristic. A passcode can be changed as needed. However, passcodes suffer from the problem that they can be stolen using keyloggers, cameras or guessed by unauthorized persons. Passcodes can also be disclosed to an unauthorized person through carelessness or inadvertence.